The ripples in space-time created by black holes have taught us a lot.

Black holes have a number of information about them: their mass, their spin, and their orientations.

Scientists have found that most of the crashes we've seen have been between black holes. The two black holes were created when a pair of massive stars turned into black holes.

One of the mergers detected so far is very odd. The ripples in the space-time were unlike anything else.

Rossella Gamba is an astronomer at the University of Jena in Germany.

She says, "GW190521 was initially analyzed as the merger of two rapidly rotating heavy black holes approaching each other, but its special features lead us to propose other possible interpretations."

The duration of the signal was difficult to explain.

Waves are created by the merger of two black holes. Stronger ripples are sent out as two black holes move closer to one another.

The shape and brevity of the signal lead us to theorize that there was an instantaneous merger between two black holes.

There are many ways to end up with a pair of black holes.

The two were together for a long time, possibly from the formation of baby stars from the same piece of cloud in space.

The other is when two objects in space pass each other in a way that makes them collide.

Gamba and her colleagues created simulations to test their hypothesis. They smashed together pairs of black holes to try to reproduce the weird signal detected in 2019.

The two black holes were caught in each other's web and slammed together to form one larger black hole, according to their results. The black holes in this scenario did not spin.

Matteo Breschi, astronomer at the University of Jena, says that a highly eccentric merger in this case explains the observation better than any other hypothesis.

There is a chance of error of over one thousand.

The team says that this scenario is more likely in a dense area of space, such as a star cluster.

There are previous discoveries about this track. The mass of the Sun was measured at 85 times the black hole's mass.

Black holes over 65 solar mass can only be formed through mergers between two lower-mass objects, according to our current models.

One of the black holes is still outside the single star core collapse formation pathway, despite the fact that the mass of the two black holes is slightly lower than previous estimates.

Hierarchical mergers, in which larger structures form through the continuous merging of smaller objects, are more likely in a cluster environment.

The data collected by LIGO and Virgo seems to support the idea that black holes are very rare. The new work suggests that GW190521 is the first we've found.

There could be more in the future. The observatory will come online again in March of 2023 after being upgraded. Two LIGO detectors in the US and one in Italy will be joined by KAGRA in Japan for more observing power.

It would be amazing if there were more detections.

The research was published in a journal.